50 lines
1.1 KiB
Go
50 lines
1.1 KiB
Go
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package crypto
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import (
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"bytes"
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"crypto/aes"
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"crypto/cipher"
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"crypto/ecdsa"
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"crypto/rand"
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"github.com/ethereum/go-ethereum/crypto"
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)
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func GenerateECDHSharedSecret(priv *ecdsa.PrivateKey, pub *ecdsa.PublicKey) []byte {
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x, _ := crypto.S256().ScalarMult(pub.X, pub.Y, priv.D.Bytes())
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return x.Bytes()
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}
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func OneShotEncrypt(pubKeyData, secret, data []byte) ([]byte, error) {
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data = appendPadding(16, data)
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iv := make([]byte, 16)
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_, err := rand.Read(iv)
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if err != nil {
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return nil, err
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}
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block, err := aes.NewCipher(secret)
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if err != nil {
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return nil, err
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}
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ciphertext := make([]byte, len(data))
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mode := cipher.NewCBCEncrypter(block, iv)
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mode.CryptBlocks(ciphertext, data)
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encrypted := append([]byte{byte(len(pubKeyData))}, pubKeyData...)
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encrypted = append(encrypted, iv...)
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encrypted = append(encrypted, ciphertext...)
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return encrypted, nil
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}
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func appendPadding(blockSize int, data []byte) []byte {
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paddingSize := blockSize - (len(data)+1)%blockSize
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zeroes := bytes.Repeat([]byte{0x00}, paddingSize)
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padding := append([]byte{0x80}, zeroes...)
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return append(data, padding...)
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}
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